Although I like the sentiment, respectfully, this would be the wrong target and strategy. Letters should be to support President Bush, and by extension, Secretary Rice and Rumsfeld. Powell is one wheel of a left running machine and the whole thing has to be derailed, not just him.
I'm not a huge Novak fan but it takes a lot of guts to call him a liar, which is what's happening by the left. Still, Powell is not the one to contradict. The targets have to be all the Democrats and those RINO's who support the left.